Precisely for the reasons cited by Matto. Detraction involves the revelation of a SECRET or HIDDEN fault. This accusation of pride was based on your public posting and not based on some personal knowledge that is known to the accuser alone. Call it a false accusation, perhaps even calumny, but it's not detraction.
I would disagree with how things went down. If one were to make a judgment based on the original post (accusation of pride), then it might be a "public" revelation about THAT post. And, even so, one would need to interpret that same post the same way to make the same judgment (in fact, we have seen that a number of posters in the original thread that did NOT judge it the same way).
I would say that when someone refers to LT's POSTING HISTORY here, then that is at least detraction despite the fact that all of his posting history is technically "public". Why? Because there are many members and lurkers here, many new posters in fact, that may not be aware of "LT's posting history". Heck, I've been here a long time and I am not aware of all of his posts. So, in that sense, it was a revelation of a supposed hidden fault.
If we're all honest with ourselves, we know that none of us are blameless and none of our posting histories are spotless. In fact, I suspect that each and every one of us are.....prideful at least at times.
The whole matter is....ironic.